U.S. Pat. No. 4,625,712 discloses a miniature high-speed axial flow intravascular blood pump percutaneously inserted and powered through a drive cable from outside the patient's body for emergency or other temporary heart assist.
It would be highly desirable to provide compact pumps of this type for patients needing long-term (chronic) heart assist. Such pumps are much more anatomically compatible than the large implantable heart assist pumps currently being developed. They also have the potential for much lower manufacturing costs.
Unfortunately, the design of fully implantable axial flow blood pumps with a self-contained motor presents major problems. The approach discussed in U.S. Pat. No. 4,625,712 utilizes the fluid flow of a purged fluid seal to prevent entry of blood elements into the pump. Supplying such a purge fluid from within the body presents major technical challenges. Percutaneous supply of the purge fluid degrades the patient's quality of life and provides a potential infection entry site.